In the traditional public switched telephone network (PSTN), the addition of a new service frequently required the upgrading of switching equipment and software. This was frequently an expensive and complex process. As new telecommunication services were developed and became widely available, the need to reduce the overhead for using services increased, along with the need to simplify maintenance and service upgrades. These needs led to the development of the Intelligent Network (IN) concept.
The IN concept provides a centralized system that separates services from switching equipment. Thus, a provider may introduce a new service without performing a major modification on multiple switches. In an IN architecture, separate service data is stored in a centralized database outside of IN switching nodes. An IN architecture also separates service programs (or service logic) and defines protocols that permit the interaction between switching systems and intelligent nodes.
The current state of IN development is Capability Set 2 (CS-2). CS-2 enables interworking between IN architectures to provide international services, allows management of both IN services and IN equipment, and supports enhanced IN services, such as mobility services. As in a CS-1 switch, all service requests received in a CS-2 IN switch are sent to an external application for processing.
Redundancy is an important requirement in real-time call processing systems, including Intelligent Network switches. When a call processing server or call application node fails, some backup mechanism should be available to handle existing calls and to process new calls. Redundancy is often implemented in hardware by having two central processing units (CPUs) executing the same set of machine instructions. If the main CPU fails, the backup CPU takes over.
However, there are disadvantages to providing call processing redundancy using redundant hardware. When hardware is upgraded to support more call processing capacity, new redundant hardware must also be added to backup the main hardware. Moreover, the use of customized fault tolerant hardware throughout the system is tremendously expensive and results in a competitive disadvantage.
Therefore, there is a need in the art for an improved Intelligent Network (IN) switch. In particular, there is a need for a CS-2 IN switch that has improved reliability with relying on hardware redundancy.